With increase of needs for various games, various gaming machines have been developed, and as an example, a slot machine which is used for casino game is one of gaming machines.
A gaming machine such a slot machine is provided with a plurality of reels on which symbols such as pictures or numbers are displayed, and takes a game rule that a game result is determined by combination of symbols displayed on the reels.
Recently, a liquid crystal display panel is used in a gaming machine having such a reel, and information for proceeding game or advertisement is displayed on the liquid crystal display panel.
A liquid crystal display panel is disposed in front of the reel, and in this case, symbols displayed on the reel which is disposed behind the liquid crystal display panel can be seen from the front of the liquid crystal display panel. For this function, several methods have been suggested. For example, in Korea Patent Publication No. 10-2007-0055766 (title: gaming machine having display screen), a light guide plate of a backlight unit of a liquid crystal display is made of transparent or translucent material and scratch or dot pattern is not formed on area of the light guide plate corresponding to symbol display area of the reel so that symbols of the reel can be seen from the front of the liquid crystal display through the area where the pattern is not formed, and in Korea Patent Publication No. 10-2006-0049328 (title: gaming machine), area of a diffuse sheet, a light guide plate, and a reflector of a backlight unit corresponding to symbol display area of the reel is removed and thus symbols of the reel can be seen from the front of the liquid crystal display.
However, a method suggested in Korea Patent Publication No. 10-2007-0055766 has a problem in that the area of the light guide plate on which scratch or dot pattern is not formed may deteriorate the function of uniform light penetration of the light guide plate so as to deteriorate light efficiency of the backlight unit. And, a method suggested in Korea Patent Publication No. 10-2006-0049328 has a problem in that images cannot be displayed on openings existed in the diffuse sheet, a light guide plate and a reflector and images cannot be displayed on the openings when game using the reel is not performed.
Backlight units which can be applied to these game machines have been disclosed in Korean Patent Registration No. 10-1024657 (title: dual display type displace device with function of display screen division), Korean Patent Publication No. 10-2012-0040005 (title: backlight unit with function of dual display), Korean Patent Registration No. 10-1047597 (title: dual light waveguide), Korean Patent Registration No. 10-0989401 (title: backlight unit with function of dual display), Korean Patent Registration No. 10-0984804 (title: backlight unit with function of dual display), or the like, but there are problems in that members such as a light waveguide are disposed in front of a reel so that the reel cannot be clearly seen, separate light sources should be added to the light waveguide, and the structures are complicated.